Vesicovaginal and Ureterovaginal Fistula Workup

If the presence of a vesicovaginal or ureterovaginal fistula is in doubt, vaginal secretions and fluid pooling in the vaginal vault should be sent for creatinine level evaluation. Serum creatinine should be drawn simultaneously, and that level should be compared with the fluid creatinine. If the fluid creatinine level is significantly higher than the serum creatinine, this confirms that the fluid is urine. If fluid creatinine test result is equivocal but a fistula is still suspected, proceed with a complete fistula workup, as discussed below.

Urinalysis and urine culture are used to rule out coexisting urinary tract infection.

Electrolyte panel (Chem 7) is used to evaluate renal function.

Complete blood cell (CBC) count is used to rule out systemic infection.

Radiographic imaging should include intravenous pyelography (IVP) or CT urography to rule out coexisting ureterovaginal fistula or ureteral obstruction. When a ureter is involved in the margin of the vesicovaginal fistula, IVP may demonstrate a standing column of contrast within the ureter, extravasation of contrast around the distal ureter, or hydronephrosis.

Cystography often demonstrates contrast leaking from the fistula tract. This confirms the presence of vesicovaginal fistula.

• Double dye test

  • Frequently, the double dye test is useful for diagnosing vesicovaginal fistula.
  • In this test, the patient ingests oral phenazopyridine (Pyridium), and indigo carmine or methylene blue is instilled into the bladder via a urethral catheter. Pyridium turns urine orange, and methylene blue (or indigo carmine) turns urine blue.
  • A tampon is placed into the vagina. If the tampon turns blue, suspect vesicovaginal fistula. If the tampon turns orange, suspect ureterovaginal fistula. If the tampon turns blue and orange, suspect a combination of vesicovaginal and ureterovaginal fistulas.

• Cystoscopy

  • Cystoscopy with concurrent vaginal speculum examination helps determine the location and size of the fistula in relation to the vaginal cuff, trigone, and ureteral orifices. In addition, it reveals the degree of inflammatory reaction and the number of fistulas present.
  • Most fistulas discovered after hysterectomy are located immediately behind the interureteric ridge and on the anterior vaginal vault.
• Retrograde pyelography

  • This is the most definitive test to determine the presence of ureterovaginal fistula.
  • Retrograde pyelography must be performed if IVP findings are abnormal or if the fistula site is difficult to locate.
  • Performing bilateral retrograde ureteropyelography is often important because both ureters may be injured.

If the fistulous tract is excised as part of the repair technique, the specimen should be sent for pathologic evaluation to review the histologic findings. Pathologic findings vary depending on the cause of the fistula and may include foreign body,^[3] giant cell reaction, malignancy, or chronic inflammation.

Giant cell reaction may be present if a foreign body was part of the cause of the fistula (eg, a nonabsorbable suture ligature of a uterine vessel catching the vaginal cuff and the bladder wall).

Radiation-induced fistulas are due to late changes caused by the radiation. After cessation of radiation therapy, fibrosis occurs in the bladder lamina propria. As fibrosis occurs in the subepithelial tissues, hyalinization of the connective tissues occurs. Often, large bizarre fibroblasts, ie, radiation fibroblasts, are encountered. An obliterative arteritis may be observed in medium-to-small vessels. These vascular changes may result in atrophy or necrosis of the bladder epithelium, causing ulceration or the formation of fissures.

Fistulas due to cervical carcinoma may demonstrate either squamous cell carcinoma or adenocarcinoma. Fistulas due to iatrogenic injury manifest as signs of acute and chronic inflammation. The presence of abundant neutrophils suggests an acute inflammatory response. In patients with chronic inflammation, the predominantly lymphocytic infiltrate is associated with macrophages. In addition, interstitial tissue fibrosis and necrosis may be present.